1. Field of the Invention
The present invention relates to an apparatus for independently controlling a motor, such as, for example, a fan motor, together with a lighting source contained within the same enclosure as the motor and coupled to the motor. The invention also relates to a communication scheme for communicating over a power line to control the load, such as, for example, a fan motor and a light.
2. Description of the Related Art
It is often desirable to include a lamp and a fan motor in a single enclosure. Since the lamp and the fan motor are often wired in parallel, the lamp and the fan motor are generally controlled together from a switch located remotely from the lamp and the motor. FIG. 1A shows a prior art light and fan motor control system 10. The system 10 includes a maintained switch 12 coupled between an alternating-current (AC) voltage source 14 and two loads, i.e., a fan motor 16 and a lighting load 18, in an enclosure 19. The fan motor 16 and the lighting load 18 are connected in parallel such that when switch 12 is closed, the fan motor 16 and the lighting load 18 will both be on, and when the switch 12 is open, the fan motor 16 and the lighting load 18 will both be off.
There are also various schemes for independent control of a fan motor as well as a lighting load from a remote location such as a wallstation. FIG. 1B shows a prior art light and fan motor control system 20, having a dual light and fan speed control 22 coupled to the AC voltage source 14. The dual light and fan speed control 22 has two outputs: the first coupled to the fan motor 16 and the second coupled to the lighting load 18, to allow for independent control of the loads. Further, the dual light and fan speed control 22 includes a fan speed circuit for adjusting the speed at which the fan motor 16 turns and a dimmer circuit for changing the intensity of the lighting load 18. The dual light and fan speed control 22 is often mounted in a standard electrical wallbox and includes a user interface to allow a user to separately control the lighting load and the fan motor.
However, the dual light and fan speed control 22 requires two separate wires to be connected between the lamp and the fan motor. If these two connections are not provided between the wallbox and the enclosure containing the lamp and the fan motor, independent control of the lighting load 18 and the fan motor 16 will not be possible. Further, in the control system 20 of FIG. 1B, it is only possible to have one dual light and fan speed control 22, and thus, only one user interface to allow for adjustment of the intensity of the lighting load 18 and the speed of the fan motor 16. Control of the fan motor 16 and lighting load 18 from more than one location is not possible in this system.
FIG. 1C shows a prior art power-line carrier (PLC) control system 30. Power-line carrier control systems use the power system wiring to transmit control signals at high frequencies (i.e., much greater than the line frequency of 50 Hz or 60 Hz). All devices of the PLC system 30 are coupled across an AC power source 32 (from hot to neutral) to receive both power and communications from the same wiring. The system 30 includes a PLC fan motor controller 34 coupled to a fan motor 36, a PLC light controller 38 coupled to a lighting load 40, and a remote control keypad 42. The remote control keypad 42 is operable to transmit a message across the power line to the PLC fan motor controller 34 and the PLC light controller 38 to control the respective loads. One example of a communication protocol for home automation using power-line carrier technology is the industry standard X10. The X10 protocol uses a voltage carrier technique to transmit messages between devices connected to the power system. Through the voltage carrier technology, the messages are transmitted on voltages signals referenced either between the hot and neutral connections of the AC power source 32 or between the hot connection of the AC power source and an earth ground connection. The devices in an X10 system communicate using house addresses and unit addresses.
However, existing power-line carrier systems have some limitations. For example, all devices in a PLC system require a neutral connection. Also, since the X10 protocol utilizes voltage carrier technology, communication messages are transmitted throughout the power system and it is difficult to isolate the communication signals from other devices connected to the power system. Finally, the X10 protocol is not a “reliable” communication scheme since no acknowledgements are sent to a transmitting device when a receiving device has received a valid message.
Thus, it is desirable to provide a reliable means to independently control from a remote location a fan motor and a lighting load that are located in the same enclosure. Since a consumer may wish to locate the fan motor and the attached lamp in a position previously occupied by only a lamp controlled by a standard single-pole single-throw (SPST) wall switch, it is desirable to be able to control a fan motor as well as an attached lamp independently, using a two-wire control device. A two-wire device is a control device that has only two electrical connections, i.e., one for the AC source voltage and one for the fan/lamp, and does not have a neutral line connection. As shown in FIG. 1A, this kind of system typically only includes the switch 12 in series electrical connection between the AC source 14 and the loads, and no neutral connection is available in the electrical wallbox where the switch is housed. Since it is desirable to control the fan motor 16 and the lighting load 18 independently, using the existing building wiring, it is necessary to develop a means to allow independent control over the existing building wiring consisting of a single wire connecting the wall control, i.e., the dual light and fan speed control 22, to the enclosure of the fan motor 16 and the lighting load 18.
Prior art systems to accomplish this are known which provide a coding/communication scheme to independently control the fan motor and the lamp. However, many of these systems are unreliable, provide erratic, noisy operation, and require a neutral connection. It is desirable to provide a simple, reliable communication scheme for independently controlling the fan motor and lamp without a neutral connection.